PS101 Chapter 4,5,6.docx

Chapter 4
The Nervous System
Function: gather & process info, produce responses to stimuli, and coordinate the workings of
different cells
The Central Nervous System (CNS): receives, processes, interprets and stores incoming sensory
information about tastes, sounds, smells, colour, pressure on skin, state of internal organs, etc. &
sends it to muscles, organs
 Sends messages for muscles, glands & internal organs
 Made of 2 components:
1. BRAIN: controls reflexes above the neck
2. SPINAL CORD: collection of neurons & supportive tissue running from the base of
the brain down the centre of the back  an extension of the brain
o Controls reflexes below the neck
o acts as a bridge for brain & other body parts
o Spinal reflexes: products of spinal cord & are automatic, not requiring any
conscious effort  can sometimes be influenced by thoughts & emotions (e.g.
erection/ejaculation)
The Peripheral Nervous System (PNS): contains all portions of the nervous system outside the
brain & spinal cord and handles the central nervous system’s input/output
1. Somatic Nervous System aka Skeletal Nervous System
 Subdivision of PNS that connects to sensory receptors & skeletal muscles
 Voluntary movement
 Consists of nerves connected to sensory receptors
 Sensory nerves: responsible for the intake of sensation & sending them to CNS  they
carry messages from special receptors in internal/external sense organs which put us in
touch with outside world and bodily activity
 Motor nerves: carry orders from CNS to muscles, glands, and internal organs (interchange)
– enable us to move & cause glands to secrete hormones
2. Autonomic Nervous System (self-governing)
 Subdivision of PNS that regulates internal organs/glands
A. Sympathetic Nervous System
 Prepares body to expend energy for fight/flight/cope response: mobilizes bodily
resources & increases output of energy during emotion/stree
 Dilates pupils & bronchial tubes, increases heart rate, blood flow, epinephrine &
norepinephrine secretion, stimulates sweat, relaxes bladder wall, inhibits digestion
B. Parasympathetic Nervous System
 Restores & conserves energy after emergency situation
 Back to stasis to function adequately
 Cortisol gets released
Neurons/nerve cells: a cell that conducts electrochemical signals; the basic unit of the nervous
system  transmits info to, from & within CNS
 Fibres of neurons are connected together in bundles called nerves – human body has 43
pairs of peripheral nerves; 12 pairs in head called cranial nerves
 The more neurons you have, the more you’ve experienced  The more axons & dendrites you have, the more complex learning connections have
occurred
 Neurogenesis: the production of new neurons from immature stem cells
 Stem cells: immature cells that renew themselves & have the potential to develop into
mature cells
1. Dendrite: incoming message (from neurotransmitters) is received by dendrite
2. From dendrite to cell body: initial processing is done in cell body
3. To axon: long thin fibre that transmits messages away from the cell body & to other
neurons/muscle/gland cells; covered by:
a. Myelin sheath: fatty insulation that may surround axon of a neuron
 Protection: prevents signals from adjacent cells from interfering with each other
– if not, results in loss of sense & lack of coordination
 Speed: speeds up conduction of neural impulses
 Made up of:
i. Glia cells: cells that support, nurture & insulate neurons, remove debris
when neurons die, enhance formation and maintenance of neural
connections & modify neuronal functioning
ii. Node: message jumps from node to node
4. To axon terminal – deposits info on the receiving neuron – doesn’t touch the receiving
neuron, instead there is a synapse Communication between Neurons
5. Synapse: the site where transmission of a nerve impulse from one nerve cell to another
occurs
a. Synaptic cleft: where axon terminal of one neuron nearly touches the dendrite or
cell body of another
b. Synaptic vesicles house neurotransmitter cells: chemical substance that is released
b a transmitting neuron at the synapse and that alters the activity of a receiving
neuron
6. How do they open/close? Action potential: electrical impulse caused by changes in voltage
that allow synaptic vesicle to open
7. Message is accepted by dendrite of receiving cell if neurotransmitter fits the receptor site 
when molecules bind to receptor sites, the electrical state of the receiving neuron changes &
neuron becomes either more likely to fire an impulse or less likely to
 Neurons are either ALL or NONE/ON or OFF = they fire or they don’t  messages
are either excitatory (positive voltage shift) or inhibitory (negative voltage shift).
 Only when a cell reaches a certain threshold will it fire.
 Thousands of messages are received by cell & it must average them
 The message that reaches a final destination depends on rate at which neurons are
firing, how many are firing, what types are firing, their location & degree of
synchrony among neurons, NOT how strongly the individual neurons are firing. Plasticity: the brain’s ability to change and adapt in response to experience – for example, by
reorganizing or growing new neural connections – rewiring of the brain to adapt to damage (e.g.
adapting to blindness by recruiting visual areas to take part in activities involving hearing)
 Brain is a dynamic organ: its circuits are continually being modified in response to info,
challenges, & changes in environment
Chemical Messengers in the Nervous System
TYPE FUNCTION EFFECTS WHERE PRODUCED
Neuro- Enable neurons to Diverse, depending on which Brain, spinal cord,
transmitters excite or inhibit each circuits activated/suppressed. Can peripheral nerves,
other. affect mood, memory, and well- certain glands
Travel through axons, being – level of effect depends on
fast/short distance. level or neurotransmitter, location,
type of receptor it binds with.
Endorphins Usually modulate the Reduce pain, promote pleasure; Brain, spinal cord
effects of linked to memory & other
neurotransmitters functions
Hormones Chemical substances Diverse, rangeing from promotion Primarily produced and
that affect functioning of digestion to metabolism secreted by endocrine
of target organs & regulation glands. Released
tissues. directly into
bloodstream, which
carries them to
organs/cells. Neurotransmitter Hormones
Seratonin: sleep,apetitie,sensory Melatonin: "dracula"hormone,
perception,temperatureregulation, secretedy pineal gland & helps
pain suppression& mood(too little = regulate daily biologicalrhythm &
depression) promotes sleep
Dopamine:voluntary movement, Oxytocin: secretedby pituitarygland.
learning, memory,emotion,pleasure highestpeak at orgasm & releasedin
or reward & responseto novelty (too pair-bondingsituationsalong with
little = parkinsons,too much= vasopressinwhichpromotoes
schizophrenia) attachment/trust
Acetylcholine:muscleaction,cognitive Adrenals: secretedby adrenal glands &
functionung,memory& emotion(too releasedduring emergency response
little = alzheimer's) (cortisol,epinephrine&
noreinephrine)
Norepinephrine:emergency response
& learning, memory,deaming, waking, Sex hormones:secretedby tissuesin
emotion gonads & by adrenal glands
GABA: amjor inhibitory testosterone:enhances sexualdesire
neurotransmitterin brain (too much= in both sexes & masculinizationof
sleep disorders,too little = anxiety) body
Glutamate:major excitetory
neurotransmitterin brain, long-term estrogen: physicalfeminization
memory
Endorphins:body's natural morphine,
body's pain killer. Role in apetitie, progesterone:present when egg is
sexual activity,blood pressure,mood, fertilized,responsibleto make uterine
learning & memory. wall comfy Mapping the Brain
Method What is Learned
Case studies of person How damage to or loss of neural circuits affects behaviour/cognition
with brain damage
Lesion studies How damage to or loss of neural circuits affects behaviour from
(animals) destroying a part of the brain to examine subsequent behavioural deficit
Electrical recordings Patterns of electrical activity in the brain – done by putting electrical
(EEGs) contacts on head & measuring activity
Needle electrodes and More precise info about electrical activity in small groups of
microelectrodes neurons/single neurons
Transcranial magnetic What happens behaviourally when a brain area is temporarily inactivated
stimulation (TMS) – done by putting a wire coil on person’s head & producing a magnetic
field
PET scans Visually displayed info about active/quiet areas during and
activity/response and about changes associated with disorders as they are
happening – done by injections of glucose laced with radioactive element
MRI Visually displayed info about brain structures – done through powerful
magnetic fields & radio receivers
Functional MRI Visually displayed info about active/quiet areas during and
activity/response and about changes associated with disorders
Parts of the Brain 1. Cerebral cortex: thin cap that goes over cerebrum – the outer layer, has c-shaped
structures, grey matter (cell bodies) and white matter (myelin-covered axons), contains
3/4s of cells
2. Cerebrum: largest part of the brain, covered by cerebrum cortex – made of left & right
cerebral hemispheres connected by corpus callosum
 Where higher-order thinking takes place
a. Corpus callosum
3. Thalamus (aka traffic cop): sends sensations (except smell – it has olfactory bulb) to
appropriate place, relays sensory info to cortex (e.g. hearing goes to auditory cortex)
4. Hypothalamus: regulates hunger, thirst, sex drives, emotion, reproduction, body
temperature, hormones & operations of autonomic nervous system. It sends messages to
pituitary gland and then pituitary gland tell other endocrine glands.
5. Pituitary gland: controlled by hypothalamus and tells other endocrine glands to release
hormonal messages
6. Limbic system: encompasses hypothalamus, amygdala and hippocampus – all of which are
implicated in emotional reactions and motivated behaviour but not for sure controlling
them
7. Amygdala: evaluates if you should really be afraid of something. Evaluates “is this really an
emergency?” Involved in the arousal and regulation of emotion & initial response to sensory
info. Formation and retrieval of emotional memories. Damage to the amygdala can result in
anxiety disorders.
8. Hippocampus: evaluates sensory information & linked memory. (e.g. hearing a bird chirp
does not trigger a reaction because body is used to it). Also enables us to form spatial
memories to accurately navigate through environment. Information about memory directed
to appropriate areas. Olfactory bulb & hippocampus are strongly linked = smell/memory
have strong relationship.
9. Cerebellum: important for smooth movement, balance, time keeping. Alcohol impairs it
from functioning (e.g. why they have sobriety road tests)
10. Brain stem: includes pons, medulla and reticular activating system
11. Pons: involved in sleeping, walking, dreaming
12. Medulla: responsible for autonomic functions like breathing and heart rate. If damaged =
dead.
13. Reticular activating system: alertness, consciousness, arouses cortex and screens
incoming information. If damaged = coma.
Cerebral Cortex
1. C-shaped structures
2. Hills and valleys
Both result in a greater mass of neurons to fit in a smaller space
Hemispheres: both share functions, but one is often more dominant: left = language, right = spatial
ability, humour. However, most behaviours require both hemispheres (e.g. understanding language
in order to get humour). Left hem controls right side, right hem controls left.
Lateralization: specialization of the two cerebral hemispheres for particular operations
3. Frontal Lobe: complex decision making, involved in short-term memory, higher-order
thinking, social judgment, emotion, ability to make plans, think creatively, take initiative,
ability to do a series of tasks in proper sequence & stop doing them at the right time
a. Pre-frontal cortex: has ability to control emotions, reasoning, decision making &
planning (speculation on association to personality)
b. Motor cortex (movement): more is allotted to parts that require more movement
c. Broca’s area: handles speech production 4. Parietal Lobe: pain, pressure, touch, attention
a. Somatosensory cortex: what allows us to sense – receives signals from body parts,
large area dedicated especially to hands and face
5. Occipital Lobe: contains areas that receive visual information
a. Visual cortex: if damaged, can cause impaired visual recognition or blindness
6. Temporal Lobe: involved in memory, perception & emotion
a. Auditory cortex: processes sound
b. Wernicke’s area: involved in language comprehension
Example: Listening to music activates the whole brain
 Temporal lobe: hearing the song
 Frontal lobe: process info in patterns
 If it’s familiar: hippocampus is remembering the song
 Cerebellum: if you want to dance
 Parietal lobe: slow-dance, touching someone
 Hypothalamus: dopamine release from hearing music we like
Understanding the Hemispheres VIA Split Brain
Split brain: happens because of a severed corpus colosum, done sometimes to prevent severe
epilepsy
1. Images in left visual field get sent to right hemisphere. Images in right visual field get sent to
left hemisphere.
2. R Hem  L body Verbal left hem.
L Hem  R body
He saw nothing because the image went to the hemisphere less capable of processing language.
He can pick it up with left hand because the right hemisphere controls the left hand. He can answer here because the image is sent to the hemisphere that allows him to answer verbally
& process language.
The Brain and…
…The “Self”
“is the brain the self?” (e.g. hippocampus & memories, limpic system & emotions related to those
memories)
The self exists in that many parts of the brain are activated by it.
…Culture
Culture is an experience that creates neural connections (e.g. bilingual brains are different than
monolingual brains)
What we focus on or learn can affect brain organization. Different cultures show different areas of
the brain responsible for difference behaviours.
…Sex
No statistical differences between math skills, etc.
Evolution: environment changes your biology.
If we culturally impose experience on men & women, their physical brain structure can change (e.g.
teaching women to focus on emotions & men not to)
Chapter 5: Body Rhythms and Mental States
Consciousness: awareness of oneself and the environment
Biological rhythm: a periodic more or less regular fluctuation in a biological system; may or may
not have psychological implications
Circadian Rhythms: a biological rhythm with a period of about 24 hours
 Entrainment: the synchronization of biological rhythms with external cues, (e.g. wake up
when daylight, sleep to darkness)
 Endogenous: generated from within rather than by external cues
o Alertness
o Body temperature (increase then sharp decline before sleeping)
o Secretion of growth hormones
Your Biological Clock
Suprachiasmatic nucleus (SCN) aka master pacemaker: an area of the brain containing a biological
clock that governs circadian rhythms
 Eye sends message to SCN [light/darkness sends message to eye receptor (SCN)].
 SCN sends message to brain/body to release hormones (e.g. melatonin secreted by pineal
gland) which has effect on brain and behaviour & receives feedback from neurotransmitters
& hormones that affect its functioning.
 Melatonin in older adolescents kicks in an hour later than younger adolescents.
 These rhythms affect us on a daily.
Internal desynchronization: a state in which biological rhythms are not in phase with one another
(e.g. jetlag affects energy level, mental skills and motor coordination)
Sleep Stages (Ultradium Rhythms) – 90 minutes
Awake: Small rapid brainwaves, inconsistent (up & downy) Stage 1: small irregular waves, drifting in/out of sleep, heart rate & breathing slows down, where
jerky muscle thing happens
 Easily woken, where lucid dreams occur
Stage 2: less easily awoken, if woken, won’t remember sleeping or having been asleep
 Sleep spindles: some brain activity
 consolidation of memory of muscles, brain puts motions together smoothly & works out
how muscles come together in a pattern *important for athletes, dancers, kids
Stage 3 (deep sleep): Delta waves appear; more relaxation of waves
 deep breathing, muscles start to relax
Stage 4 (deep sleep): Delta waves have taken over; need a big noise to awaken you
 sleepwalking occurs in this stage (or 3) because paralysis hormones have not yet been
released in the body
 Delta brain waves only occur when drunk, have dementia or schizophrenia
REM stage: Rapid Eye Movement (dream stage)
 Where we dream & where dreams are remembered
 Brain waves are mostly similar to awake waves but body is acting very different (sometimes
called paradoxical sleep): paralysis hormone has been secreted = no sleepwalking
 Heart rate & blood pressure increases
 Genitals are very active (wet dreams)
 REM sleep may be necessary for memory: consolidation
 When people are deprived of REM, they will make up for it when the